1. Field of the Disclosure
The present invention relates to a power converting system having a battery energy storage apparatus and a configuration of a battery, and particularly to a battery device that is capable of operating without any hitch particularly even when a battery device is out of order and of increasing stability of an energy storage apparatus and an energy storage system including the battery device.
2. Background of the Disclosure
A demand for electric power gradually increases with industrial developments and there are ever-increasing gaps between day and night electric power usages, seasonal electric power usages, and daily electric power usages.
For this reason, rapid progress has been made in developing technologies that can reduce peak load by utilizing surplus electric power of an electric power system. Of these technologies, the most typical is associated with a battery energy storage system that stores the surplus electric power of the electric power system in batteries or reversely supplies electric power from the batteries to the electric power system when the electric power system runs short of electric power.
The battery energy storage system stores the surplus electric power that is generated at night, or the surplus electric power that is generated using new renewable energy, such as wind power and sunlight, and supplies the electric power stored in the batteries to the electric power system when the peak load or an accident occurs in the electric power system. Accordingly, the utilization of the new renewable energy stabilizes the unstably-punctuating supply of the electric power from the electric power system, and thus reduces the maximum load and accomplishes leveling-off of the load.
A battery device and an energy storage apparatus including the battery device in the related art are described below referring to FIGS. 1 and 2.
FIG. 1 is a diagram illustrating a configuration of the energy storage apparatus in the related art. FIG. 2 is a diagram illustrating a configuration of the battery device in the related art.
Referring to FIG. 1, the energy storage apparatus includes a 3-phase source 101, a transformer 102, and a power converting system (PCS) 103, and a battery device 104.
The 3-phase source 101 is a 3-phase power source that has a line-to-line root mean square (RMS) of 100V or more. In the 3-phase source 101, the presence or absence of the 3-phase power source is optional.
The transformer 102 is for electrical insulation and for changing voltage to different levels. Installation of the transformer 102 is also optional.
The power converting system 103 is a system that performs power conversion between a direct current (DC) power source, which is a battery, and an input 3-phase alternating current (AC) power source and is configured from a 2 or more-level pulse width modulation (PWM) inverter and an input filter.
The battery device 104 stores or outputs direct current voltage.
Referring to FIG. 2, battery unit modules 202, 203, and 204 are connected to one another in series or in parallel. That is, battery cells of each of the battery unit modules 202, 203, and 204 are connected, as one unit, to one another in series or in parallel. The battery unit modules 202, 203, and 204, each of which has this battery cell arrangement, may be connected in series or may be connected in parallel. Accordingly, the batter device 104 as a whole has a structure in which the battery cells are connected with one another in series or in parallel.
A communication module 205 transmits battery information.
A communication line 206 is a communication line for transmitting an output signal of the communication module 205 outside of the battery.
The electric power line 207 is an electric power line over which an output voltage of the battery device 104 is output. A direct current voltage that is generated due to discharging of the battery device 104 is transmitted to the power converting system 103.
A switch 208 is formed between the power converting system 103 and the battery device 104. The switch 208 establishes or releases a connection between the power converting system 103 and the battery device 104.
Through the operation of the switch 104, the power converting system 103 performs a function of supplying to the electric power system a constant amount of electric power that comes from the energy of the battery device 104 or of charging the discharged battery with the energy of the electric power system.
At this point, if a 3-phase generation system of the 3-phase source 101 operates properly, the power converting system 103 properly follows a phase angle of the electric power system and thus outputs the same frequency and the same level of voltage as in the electric power system. Thus, the battery device 104 is discharged to supply the energy to the electric power system or the battery device 104 is charged to absorb the energy of the electric power system.
In this case, it is considered that the energy storage apparatus including the power converting system 103 and the battery device 104 is configured as one current source equivalent circuit.
In addition, if the 3-phase generation system of the 3-phase source 101 is absent, the power converting system 103 operates as a voltage source that outputs a constant voltage and a constant frequency. If an additional energy source is absent in a system in which the 3-phase generation system is not present, the battery device 104 performs only a function of making the energy discharge, and may further include a device for charging the battery in an external manner.
At this point, the energy storage apparatus including the power converting system 103 and the battery device 103 operates as the voltage source.
The power converting system 103 may include an input filter, such as an L filter, an L-C filter, or an L-C-L filter, and may possibly be configured from a 3-phase 2-level PWM inverter or a 3-phase 3-level PWM inverter.
The battery device 104 outputs the direct current voltage in a constant range and transmits pieces of information, such as a charged state of the battery, an operated state of the battery, and the extent with which the battery is discharged, to an energy management apparatus of a high-level control system or to the power converting system 103 through the communication module 205. Thus, a charged/discharged state of the battery device 104 is determined depending on an energy state of the battery.
At this point, if a sign of disorder occurs in the battery device 104, the switch 208 is opened by the energy management apparatus or the power converting system 103, and thus the connection is released between the power converting system 103. Accordingly, the operation of the entire system comes to a stop.
However, in the related art, as described, the power converting system and the battery device are connected to each other through one breaker or one switch. Therefore, if the sign of disorder occurs in a specific unit module, one of the unit modules of the battery, the operation of the entire system comes to a stop. This causes problems in terms of system management. Such problems arise from the configuration of the battery and occur due to the connection of the battery and the power converting system through one switch.